Hydraulic control system for an automatic transmission

ABSTRACT

A hydraulic control system for a transmission includes a source of pressurized hydraulic fluid that communicates with an electronic transmission range selection (ETRS) subsystem or manual valve and a clutch actuation subsystem.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/677,781, filed Jul. 31, 2012, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The invention relates to a control system for an automatic transmission,and more particularly to an electro-hydraulic control system.

BACKGROUND

A typical automatic transmission includes a hydraulic control systemthat is employed to provide cooling and lubrication to components withinthe transmission and to actuate a plurality of torque transmittingdevices. These torque transmitting devices may be, for example, frictionclutches and brakes arranged with gear sets or in a torque converter.The conventional hydraulic control system typically includes a main pumpthat provides a pressurized fluid, such as oil, to a plurality of valvesand solenoids within a valve body. The main pump is driven by the engineof the motor vehicle. The valves and solenoids are operable to directthe pressurized hydraulic fluid through a hydraulic fluid circuit tovarious subsystems including lubrication subsystems, cooler subsystems,torque converter clutch control subsystems, and shift actuatorsubsystems that include actuators that engage the torque transmittingdevices. The pressurized hydraulic fluid delivered to the shiftactuators is used to engage or disengage the torque transmitting devicesin order to obtain different gear ratios.

While previous hydraulic control systems are useful for their intendedpurpose, the need for new and improved hydraulic control systemconfigurations within transmissions which exhibit improved performance,especially from the standpoints of efficiency, responsiveness andsmoothness, is essentially constant. Accordingly, there is a need for animproved, cost-effective hydraulic control system for use in ahydraulically actuated automatic transmission.

SUMMARY

A hydraulic control system for a transmission is provided. The hydrauliccontrol system includes a source of pressurized hydraulic fluid thatcommunicates with an analog electronic transmission range selection(ETRS) subsystem. The ETRS subsystem communicates with a clutch actuatorsubsystem that engages a plurality of clutches/brakes. In anotherimplementation, the source of pressurized hydraulic fluid communicateswith a manual valve.

Further features, advantages, and areas of applicability will becomeapparent from the description provided herein. It should be understoodthat the description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of the presentdisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.The components in the figures are not necessarily to scale, emphasisinstead being placed upon illustrating the principles of the invention.Moreover, in the figures, like reference numerals designatecorresponding parts throughout the views. In the drawings:

FIGS. 1A, 1B, 1C, 1D, 1E and 1F show a hydraulic control system inaccordance with the principles of the present invention;

FIGS. 2A, 2B, 2C, 2D, 2E and 2F show another embodiment of a hydrauliccontrol system in accordance the principles of the present invention;and

FIGS. 3A, 3B, 3C, 3D, 3E and 3F show yet another embodiment of ahydraulic control system having a manual valve in accordance theprinciples of the present invention.

DESCRIPTION

With reference to FIGS. 1A, 1B, 1C, 1D, 1E and 1F, a portion of ahydraulic control system according to the principles of the presentinvention is generally indicated by reference number 100. The hydrauliccontrol system 100 generally includes a plurality of interconnected orhydraulically communicating subsystems including a pressure regulatorsubsystem 102, an electronic transmission range selection (ETRS) controlsubsystem 104, and a clutch control subsystem 106. The hydraulic controlsystem 100 may also include various other subsystems or modules, such asa lubrication subsystem, a torque converter clutch subsystem, and/or acooling subsystem, without departing from the scope of the presentinvention.

The pressure regulator subsystem 102 is operable to provide and regulatepressurized hydraulic fluid, such as transmission oil, throughout thehydraulic control system 100. The pressure regulator subsystem 102 drawshydraulic fluid from a sump 107. The sump 107 is a tank or reservoirpreferably disposed at the bottom of a transmission housing to which thehydraulic fluid returns and collects from various components and regionsof the transmission. The hydraulic fluid is forced from the sump 107 andcommunicated throughout the hydraulic control system 100 via a pump 108.The pump is preferably driven by an engine (not shown) and may be, forexample, a gear pump, a vane pump, a gerotor pump, or any other positivedisplacement pump. The pressure regulator subsystem 102 may also includean alternate source of hydraulic fluid that includes an auxiliary pump(not shown) preferably driven by an electric engine, battery, or otherprime mover (not shown). The pump 108 feeds pressurized hydraulic fluidat line pressure to a line pressure regulator valve 109. The linepressure regulator valve 109 communicates pressurized hydraulic fluid toa converter feed limit valve 110, a torque converter clutch (TCC)control valve 111, and a main supply line 112. The lubrication flowregulator valve 266 and the TCC control valve 111 each feed lubricationand TCC circuits. The main supply line 112 feeds the ETRS subsystem 104and the clutch actuator subsystem 106.

The ETRS control subsystem 104 connects the pressure regulator subsystem102 with the clutch control subsystem 106. Generally, the ETRS controlsubsystem 104 converts electronic input for a requested range selection(Drive, Reverse, Park) into hydraulic and mechanical commands. Thehydraulic commands use line pressure hydraulic fluid from the pressureregulator subsystem 102 via fluid line 112 to supply hydraulic fluid tothe clutch actuator subsystem 106. The mechanical commands includeengaging and disengaging a park mechanism 114.

The ETRS control subsystem 104 includes an enablement valve assembly120. The enablement valve assembly includes fluid ports 120A-D. Fluidport 120A is an exhaust port that communicates with the sump 107. Fluidport 120B communicates with a first mode valve assembly 134 through afeed line 121. Fluid port 120C communicates with the main supply line112. Fluid port 120D communicates with a signal line 122. The enablementvalve assembly 120 further includes a spool valve 123 slidably disposedwithin a bore 124. When pressurized fluid is supplied through the signalline 122, fluid pressure acts upon the spool valve 123 through the fluidport 120D. When the spool valve 123 is stroked, the fluid port 120Ccommunicates with the fluid port 120B.

In addition to the first mode valve assembly, the ETRS subsystem 104includes second mode valve assembly 136 that communicate in series withone another and with the enablement valve assembly 120. The first modevalve 134 includes spool valves 146A and 146B and further includes ports134A-I, numbered consecutively from left to right. Ports 134A, D, and Hare exhaust ports that communicate with the sump 107. Ports 134B and134F communicate with the range feed line 121. Port 134C communicateswith a fluid line 140. Port 134E communicates with a fluid line 142.Port 134G communicates with a fluid line 144. Port 1341 communicateswith a signal line 145.

The spool valves 146A and 146B are actuated by the hydraulic fluidprovided through lines 144 and from solenoid 263 via line 145. The spool146A is moveable between a stroked position and a de-stroked position.In the de-stroked position port 134F communicates with port 134E.Accordingly, the range feed line 121 communicates with line 142. Whenthe first mode valve assembly 134 is stroked, port 134F is closed whileport 134E exhausts and port 134B communicates with port 134C such thatthe range feed line 121 communicates with line 140.

The second mode valve assembly 136 generally includes ports 136A-M.Ports 136C, 136G, and 136L are exhaust ports that communicate with thesump 107. Port 136A communicates with the fluid line 144. Ports 136B and136J communicate with a Park feed line 150. Port 136D communicates witha sequence line 152 that communicates with port 136K. Port 136Ecommunicates with fluid line 140. Port 136F communicates with a Driveline 154. Port 136H communicates with a Reverse line 156. Port 1361communicates with fluid line 142. Fluid port 136M communicates with asignal line 158.

The second mode valve assembly 136 includes spool valves 162A and 162Bactuated by the hydraulic fluid provided through lines 144 and fromsolenoid 261 via line 158. The spool valve 162A is moveable between astroked position and a de-stroked position. In the de-stroked position,port 136E communicates with port 136F and port 1361 communicates withport 136J and port 136H exhausts. Therefore, when the first mode valveassembly 134 is stroked, the transmission is in “Drive” when the secondmode valve assembly 136 is de-stroked and is providing hydraulic fluidto Drive line 154 and to the “1 feed” line 140, which will be describedin further detail below. In the stroked position the port 136Ecommunicates with the port 136D providing signal feedback to port 136K.Also, port 1361 communicates with port 136H and feeds the Reverse fluidline 156 while ports 136B and 136F exhaust.

The first mode valve assembly 134 may include either one or two positionsensors 171, and the second mode valve assembly 136 may include a pairof position sensors 175, 179, by way of example.

A check valve 180 is connected to fluid lines 140 and 156. The checkvalve 180 includes three ports 180A-C. The check valve 180 closes offwhichever of the ports 180A and 180B that is delivering the lowerhydraulic pressure and provides communication between whichever of theports 180A and 180B having or delivering the higher hydraulic pressureand the outlet port 180C. Port 180A is connected to the Reverse fluidline 156. Port 180B is connected to fluid line 140. Port or outlet 180Cis connected to an out-of-Park (OOP) fluid line 181.

The into-Park fluid line 150 and the OOP fluid line 181 each communicatewith a Park servo valve 182. The Park servo valve 182 includes ports182A and 1828 each located on either side of a piston 184. The piston184 is mechanically coupled to the park mechanism 114. Port 182Acommunicates with the OOP fluid line 181 and port 182B communicates withthe into-Park fluid line 150. The piston 184 moves upon contact by thehydraulic fluid supplied by one of the fluid lines 181, 150, therebymechanically disengaging or engaging the Park mechanism 114.

The Park mechanism 114 is connected with an out-of-Park (OOP) solenoid186. The OOP solenoid 186 is actuatable to mechanically prevent the Parkmechanism 114 from engaging during an engine stop-start event (i.e. whenthe vehicle is intended to be mobile during an automatic engine stop).The OOP 184 solenoid may also be used to keep the Park servo 182disengaged when it is desirable to operate in Drive or Reverse at othertimes.

As noted above, the ETRS subsystem 104 feeds hydraulic fluid to theclutch actuation control subsystem 106 via the range feed line 121, theDrive line 154 and the Reverse line 156 while the clutch actuationcontrol subsystem 106 provides hydraulic control signals back to theETRS subsystem 104 via signal line 144.

The clutch actuation control subsystem 106 generally includes a clutchselect valve assembly 200 and a plurality of clutch regulationassemblies 202, 204, 206, 208, 210, and 212. Each of the clutchregulation assemblies 202-212 are associated with one of a plurality ofclutch actuators 214, 216, 218, 220, 222, and 224. The clutch actuators214-224 are hydraulically actuated pistons that each engage one of aplurality of torque transmitting devices (clutches or brakes) to achievevarious forward, or drive, speed ratios and reverse speed ratios.

The clutch select valve assembly 200 generally includes ports 200A-J.Ports 200D and 200G are exhaust ports that communicate with the sump107. Port 200A communicates with the fluid line 156. Port 200Bcommunicates with the clutch regulation assemblies 202 and 206. Port200C communicates with a clutch feed line 234. Port 200E communicateswith the feed line 154. Port 200F communicates with line 144 whichprovides a control signal back to ETRS subsystem 104. Port 200Hcommunicates with a feed line 240. Port 200I communicates with thesignal line 156. Port 200J communicates with the lines 234 and 242.

The clutch select valve assembly 200 includes a spool valve 250 slidablydisposed within a bore. The spool valve 250 is moveable between astroked position and a de-stroked position. In the de-stroked position,port 200B is closed, ports 200D and 200G exhaust, port 200C communicateswith port 200J. Therefore in the stroked position, the clutch selectvalve 200 provides hydraulic fluid to the signal line 144 and provideshydraulic fluid to clutch feed line 236. The signal line 144communicates with valve assembly 134 and valve assembly 136. The feedline 236 communicates with the clutch actuator 214. In the strokedposition port 200I is blocked. In the de-stroked position the Reversefeed line 156 feeds the feed line 240 while the feed line 144 isexhausted.

The clutch select valve assembly 200 is stroked when hydraulic fluid iscommunicated through a clutch select solenoid 260 to fluid port 200J viasignal line 242. The clutch select solenoid 260 receives hydraulic fluidfrom a feed line 262 that communicates with the main supply line 112through a feed limit valve 264. The feed line 262 also supplieshydraulic fluid to a solenoid 261 and a solenoid 263.

A check valve 270 is connected to a fluid line 267. The check valve 270includes three ports 270A-C. The check valve 270 closes off whichever ofthe ports 270A and 270B that is delivering the lower hydraulic pressureand provides communication between whichever of the ports 270A and 270Bhaving or delivering the higher hydraulic pressure and the outlet port270C.

A check valve 276 is connected to fluid lines 144 and 240. The checkvalve 276 includes three ports 276A-C. The check valve 276 closes offwhichever of the ports 276B and 276C that is delivering the lowerhydraulic pressure and provides communication between whichever of theports 276B and 276C having or delivering the higher hydraulic pressureand the outlet port 276A.

A clutch gain enable valve assembly 280 selectively communicates withthe clutch gain valve 399 via a fluid line 499. The clutch gain enablevalve assembly 280 is engaged by the fluid line 510 which is fed byclutch regulation assembly 202.

The clutch regulation assembly 202 includes a variable flow solenoid 203and a boost valve 282. The solenoid 203 is connected to the boost valve282, which, in turn, is connected to an actuator feed line 284 thatcommunicates with the clutch actuator 214.

The clutch regulation assembly 204 includes a variable flow solenoid205, a regulator valve 207A and a regulator valve 207B that areconnected to the Drive line 154. The solenoid 205 receives hydraulicfluid from the Drive line 154 and selectively communicates the Driveline hydraulic fluid to an actuator feed line 286. The regular valve207B has a hole through it to allow the signal from the solenoid 205 tocommunicate with the regulator valve 207A. The two regulator valves 207Aand 207B are separated by a fluid signal from the clutch gain valveassembly 399. This fluid line communicates with fluid signal line 242when clutch gain enable valve assembly 280 is in the stroked position.Signal line 242 is fed from solenoid 260. The actuator feed line 286communicates with the clutch actuator 216.

The clutch regulation assembly 206 includes a variable flow solenoid209. The solenoid 209 is connected to the exhaust backfill line 147 andthe drive line 154. The solenoid 209 selectively communicates theDrive/signal line hydraulic fluid to an actuator feed line 290. Theactuator feed line 290 communicates with the clutch actuator 218.

The clutch regulation assembly 208 includes a variable flow solenoid 211and a boost valve 292. The solenoid 211 is connected to the exhaustbackfill line 147 and to the line feed 112. The boost valve 292 isconnected to the line feed 112 and to an actuator feed line 294. Thesolenoid 211 receives hydraulic fluid from the line feed 112 andselectively communicates the line feed 112 hydraulic fluid to the signalline 293 in order to move the boost valve 292. The boost valve 292 inturn selectively communicates the Drive/signal line hydraulic fluid tothe actuator feed line 294. The actuator feed line 294 communicates withthe clutch actuator 220.

The clutch regulation assembly 210 includes a variable flow solenoid 213and a boost valve 296. The solenoid 213 is connected to the exhaustbackfill line 147 and to the line feed 112. The boost valve 296 is alsoconnected to the line feed 112 and to an actuator feed line 298. Thesolenoid 213 receives hydraulic fluid from the line feed 112 andselectively communicates the line feed 112 hydraulic fluid to the signalline 297 to move boost valve 296. The boost valve 296 in turnselectively communicates the feed line hydraulic fluid to the actuatorfeed line 298. The actuator feed line 298 communicates with the clutchactuator 222.

The clutch regulation assembly 212 includes a variable flow solenoid215, a regulator valve 217A and a regulator valve 217B that areconnected to the main supply line 112. The solenoid 213 receiveshydraulic fluid from the main supply line 112 and selectivelycommunicates the line pressure hydraulic fluid to an actuator feed line300, which, in turn, communicates with the clutch actuator 224. Theregular valve 217B has a hole through it to allow the signal from thesolenoid 215 to communicate with the regulator valve 217A. The tworegulator valves 217A and 217B are separated by a fluid signal from theclutch gain valve assembly 399.

Selective actuation of combinations of clutch regulator assemblies andvalve positions allows the hydraulic control system 100 to selectivelyengage combinations of the plurality of clutches and brakes.

Turning now to FIGS. 2A, 2B, 2C, 2D, 2E and 2F, another arrangement of ahydraulic control system is generally indicated by reference number 400.The hydraulic control system 400 is substantially similar to that shownin FIGS. 1A, 1B, 1C, 1D, 1E and 1F and like components are indicated bylike reference numbers. However, in the hydraulic control system 400, aclutch select valve 401 replaces the clutch select valve 200 shown inFIGS. 1A, 1B, 1C, 1D, 1E and 1F. The clutch select valve assembly 401generally includes ports 401A-L. Ports 401D, 401G and 401K are exhaustports that communicate with the sump 107 or an exhaust backfill circuit.Port 401A communicates with the fluid line 156. Port 401B communicateswith the clutch regulation assemblies 202 and 206. Port 401Ccommunicates with a clutch feed line 234. Port 401E communicates withthe feed line 154. Port 401F communicates with a clutch feed line 144.Port 401H communicates with a feed line 240. Port 401L communicates withthe signal line 156. Port 401J communicates with a check valve 402. Andport 401M communicates with the line 234.

The clutch select valve assembly 401 includes a spool valve 450 slidablydisposed within a bore. The spool valve 450 is moveable between astroked position and a de-stroked position. In the de-stroked position,port 401B is closed, ports 401D, 401G and 401K exhaust, port 401Ccommunicates with port 401M. In the stroked position, port 401K isblocked. Therefore the Reverse feed line 156 is also blocked while theclutch feed line 144 feeds feed line 240.

The clutch select valve assembly 401 is stroked when hydraulic fluid iscommunicated through a clutch select solenoid 260 to fluid port 401M viasignal line 242. The clutch select solenoid 260 receives hydraulic fluidfrom a feed line 262 that communicates with the main supply line 112through a feed limit valve 264. The feed line 262 also supplieshydraulic fluid to a solenoid 261 and a solenoid 263 that communicateswith fluid line 122.

The check valve 402 includes three ports 402A, 402B, and 402C. Port 402Acommunicates with the line 154. Port 402B communicates with port 401J ofthe clutch valve assembly 402. And port 402C communicates with theclutch regulation assemblies 204 and 206.

Turning to FIGS. 3A, 3B, 3C, 3D, 3E and 3F, another arrangement of ahydraulic control system is generally indicated by reference number 500.The hydraulic control system 400 is substantially similar to that shownin FIGS. 1A, 1B, 1C, 1D, 1E and 1F and like components are indicated bylike reference numbers. However, in the hydraulic control system 500,the ETRS subsystem has been replaced by a manual valve 502 and a defaultvalve 510. The manual valve 502 communicates with the main supply line112, the Reverse line 156, and the Drive line 154. Movement of a rangeselector 508 of an operator of the motor vehicle in turn translates themanual valve 502 between various positions including a Reverse positionand a Drive position. In the Drive position, the main supply line 112provides hydraulic fluid at line pressure to the Drive line 154. In theReverse position, the main supply line 112 provides hydraulic fluid atline pressure to the Reverse line 156.

The default valve 510 includes a spool 512 slidably disposed in a bore.As the spool 512 reciprocates within the bore, the default valveselectively communicates with the main supply line 112, the Drive line154, the Reverse line 156, and the clutch regulation assemblies 202,204, 206, 208, 210, and 212.

The description of the invention is merely exemplary in nature andvariations that do not depart from the general essence of the inventionare intended to be within the scope of the invention. Such variationsare not to be regarded as a departure from the spirit and scope of theinvention.

What is claimed is:
 1. A hydraulic control system for a ten-speedautomatic transmission, the hydraulic control system comprising: apressure regulator subsystem with a source of pressurized hydraulicfluid for providing a flow of hydraulic fluid; an electronictransmission range selection (ETRS) control subsystem including a set ofthree valve assemblies; and a clutch actuation control subsystem thatprovides pressurized hydraulic fluid to a plurality of clutch actuatorsthrough a plurality of clutch valve assemblies, wherein the ETRS controlsubsystem connects the pressure regulator subsystem with the clutchcontrol subsystem and wherein the ETRS control subsystem convertselectronic input for a requested range selection into hydraulic andmechanical commands.
 2. The hydraulic control system of claim 1 whereinthe source of pressurized hydraulic fluid is a pump.
 3. The hydrauliccontrol system of claim 1 wherein the set of three valve assemblies ofthe ETRS control subsystem includes an enablement valve assembly, afirst mode valve assembly, and a second mode valve assembly.
 4. Thehydraulic control system of claim 3 wherein the enablement valveassembly communicates with the first mode valve assembly and the secondmode valve assembly.
 5. The hydraulic control system of claim 1 whereineach of the valve assemblies of the ETRS control subsystem includesvalves slidably disposed in a bore.
 6. The hydraulic control system ofclaim 1 wherein the ETRS control subsystem further includes a spoolvalve assembly that communicates with the first mode valve assembly. 7.The hydraulic control system of claim 6 wherein the spool valves areslidably disposed in a bore.
 8. The hydraulic control system of claim 1wherein the plurality of clutch actuators includes six clutch actuators.9. The hydraulic control system of claim 8 wherein each of the clutchactuators is a hydraulically actuated piston that engages one of aplurality of torque transmitting devices to achieve a desired speedratio.
 10. The hydraulic control system of claim 1 wherein each of theplurality of clutch actuators is activated by one of a plurality ofvariable force solenoids through the plurality of clutch valveassemblies.
 11. The hydraulic control system of claim 1 wherein the ETRScontrol subsystem further a Park mechanism that communicates with anout-of-Park solenoid and a Park servo valve.
 12. The hydraulic controlsystem of claim 11 wherein the out-of-Park solenoid is actuated toprevent the Park mechanism from engaging during an engine stop-startevent.
 13. The hydraulic control system of claim 11 wherein theout-of-Park solenoid disengages the Park servo valve to operate thetransmission in Drive or Reverse.
 14. A hydraulic control system for aten-speed automatic transmission, the hydraulic control systemcomprising: a pressure regulator subsystem with a source of pressurizedhydraulic fluid for providing a flow of hydraulic fluid; an electronictransmission range selection (ETRS) control subsystem including a set ofthree valve assemblies; and a clutch actuation control subsystem thatprovides pressurized hydraulic fluid to a plurality of clutch actuatorsthrough a plurality of clutch valve assemblies, the clutch actuatorcontrol subsystem a clutch select valve assembly that communicates withthe pressure regulator subsystem, wherein the ETRS control subsystemconnects the pressure regulator subsystem with the clutch controlsubsystem and wherein the ETRS control subsystem converts electronicinput for a requested range selection into hydraulic and mechanicalcommands.
 15. The hydraulic control system of claim 14 wherein the setof three valve assemblies of the ETRS control subsystem includes anenablement valve assembly, a first mode valve assembly, and a secondmode valve assembly.
 16. The hydraulic control system of claim 14wherein the plurality of clutch actuators includes six clutch actuators.17. The hydraulic control system of claim 16 wherein each of the clutchactuators is a hydraulically actuated piston that engages one of aplurality of torque transmitting devices to achieve a desired speedratio.
 18. A hydraulic control system for a ten-speed automatictransmission, the hydraulic control system comprising: a pressureregulator subsystem with a source of pressurized hydraulic fluid forproviding a flow of hydraulic fluid; a manual valve and a default valve;and a clutch actuation control subsystem that provides pressurizedhydraulic fluid to a plurality of clutch actuators through a pluralityof clutch valve assemblies, wherein the manual valve and the defaultvalve connects the pressure regulator subsystem with the clutch controlsubsystem and wherein movement of a range selector translates the manualvalve to various Drive and Reverse positions.
 19. The hydraulic controlsystem of claim 18 wherein the plurality of clutch actuators includessix clutch actuators.
 20. The hydraulic control system of claim 19wherein each of the clutch actuators is a hydraulically actuated pistonthat engages one of a plurality of torque transmitting devices toachieve a desired speed ratio.